Shrews vary in size. Smallest mammal on the planet is Etruscan Shrew which reaches 1.3 inches in length and 0.07 ounces in weight. Most shrews reach between 2.5 and 9.5 inches in length and weigh of up to 3.5 ounces.
They have a higher metabolic rate than any other animal. The heart of the masked shrew, Sorex cinereus, beats 800 times a minute, considerably faster than that of the hummingbird.
Most shrews are terrestrial animals. Some of them live both on the ground and on the trees. Certain shrews are semi-aquatic (they live near the water). Those that live near the water have stiff hairs on the feet used for "running" across the water surface by trapping the bubbles of air.
Shrews must eat 80-90 % of their own body weight in food daily. Most will starve to death if deprived of food for half a day.
Shrew is covered with fur that can be brown or gray in color. Fur is, short, soft and thick.
They eat anything available, but prefer small animals; they are economically important as destroyers of insects and slugs that harm crops.
Shrew mainly eats insects, but it also consumes worms, fish, frogs, seed and nuts. It can also kill animals larger than its size, such as different kind of rodents. Shrews are beneficial for farmers because they eliminate insects, slugs and other pests from the crops.
Shrews are easily startled and will jump, faint, or drop dead at a sudden noise.
Shrew is known as nocturnal animal (active at night), but it is actually active both during the day and night.
The Etruscan Shrew (Suncus etruscus) which at about 3.5 cm and 2 g is the smallest living terrestrial mammal.
Shrew has the fastest metabolic rate of all known animals (even higher than hummingbird). Due to high energetic needs, shrew needs to eat almost during whole day and night. Short period of food deprivation (half a day) leads to death of the shrew.
Unlike most mammals, some species of shrew are venomous.
Heart rate of shrew reaches incredible 700 beats per minute.
Shrew venom is not conducted into the wound by fangs, but by grooves in the teeth.
Shrew can be scared to death by a sudden noise, such as thunder.
The venom of the shrew contains various compounds and the contents of the venom glands of the American short-tailed shrew are sufficient to kill 200 mice by intravenous injection.
Shrew has poor eyesight, but excellent sense of smell and hearing. Last two senses help shrew to locate its prey and avoid predators. Shrews are also very smart animals. Their brain weighs 10% of the total body weight.
They do not hibernate, but can enter torpor. Shrews can lose between 30% and 50% of their body weight in winter, shrinking the size of bones, skull and internal organs.
Shrews are often killed by other animals, but they are rarely eaten afterwards, because they release smelly musk from the gland on the belly which is repulsive for most animals.
Unlike rodents, which have gnawing incisors that grow throughout life, the teeth of shrews wear down throughout life, and they lose their milk teeth before birth.
Shrew is one of the rare venomous mammals. Poisonous saliva is delivered to their enemies (or prey) by the grooves in their teeth. American short-tailed shrew contains enough venom to kill 200 mice.
In general, shrews live in and on the ground.
Shrews are solitary animals (live on their own) that can be seen together only during mating season. Shrew aggressively chases away other shrews from its territory during non-breeding season.
Shrews are distributed almost worldwide. Of the major tropical and temperate land masses, only New Guinea, Australia, and New Zealand do not have any native shrews.
Shrews reach sexual maturity early - just 3 to 4 months after birth. Those living the tropical areas often mate during whole year. Shrews that are living in temperate areas avoid breeding during cold winter time.
Shrews have sharp, spike-like teeth, not the familiar gnawing front incisor teeth of rodents.
Pregnancy lasts between 17 and 32 days. Female can have up to 10 litters per year.
Lifespan of shrews is very short, between 12 and 30 months.